In the case in which a detection of an extremely fine substance is carried out, a wide variety of specimen material detection apparatus has been used for enabling an inspection of such a substance by putting a physical phenomenon of a substance to practical use from the past.
As one of such specimen material detection apparatuses, there can be mentioned for instance a surface plasmon resonance apparatus (hereafter referred to as an SPR apparatus) in which a phenomenon of a resonance of an electron and a light in a minute region of a nanometer level or the like (a surface plasmon resonance (SPR) phenomenon) is put to practical use and an extremely fine analyte in a biological body is detected for instance.
As one of such specimen material detection apparatuses, there also can be mentioned for instance a surface plasmon-field enhanced fluorescence spectroscopic measurement apparatus (hereafter referred to as an SPFS apparatus) in which the analyte detection can be carried out with a higher degree of accuracy as compared with the SPR apparatus based on a principle of a surface-plasmon enhanced fluorescence spectroscopy (SPFS) for putting a surface plasmon resonance (SPR) phenomenon to practical use.
For the surface-plasmon enhanced fluorescence spectroscopy (SPFS), under the condition of the attenuated total reflectance (ATR) of an excitation light such as a laser light that has been applied from the light source on a surface of a metallic thin film, by generating a surface plasmon light (a crude density wave) on a surface of a metallic thin film, a photon amount that is included in an excitation light that has been applied from the light source is increased by several ten times to several hundred times to obtain an electric field enhancement effect of a surface plasmon light.
By the electric field enhancement effect, a fluorescence substance that has been coupled (labeled) with an analyte that has been captured near a metallic thin film is excited in an efficient manner. By observing the fluorescence while using a light detection means such as a photomultiplier tube (PMT) of a photon counting system and a charge coupled device (CCD) camera, an analyte of an infinitesimal quantity and/or an extremely low concentration is detected in the above method.